Dean Richard A, Fam Hok Khim, An Jianghong, Choi Kunho, Shimizu Yoko, Jones Steven J M, Boerkoel Cornelius F, Interthal Heidrun, Pfeifer Tom A
Centre for Drug Research and Development, Vancouver, BC, Canada.
Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
J Biomol Screen. 2014 Dec;19(10):1372-82. doi: 10.1177/1087057114546551. Epub 2014 Aug 12.
Mutations of DNA repair pathways contribute to tumorigenesis and provide a therapeutic target for synthetic lethal interactions in tumor cells. Given that tyrosyl-DNA phosphodiesterase 1 (Tdp1) repairs stalled topoisomerase-I DNA complexes, we hypothesized that inhibition of Tdp1 has synthetic lethal effects in some cancers. To test this, we screened tumor arrays for Tdp1 expression and observed that Tdp1 is expressed in many tumors, including more than 90% of human breast tumors. Subsequent chemical screening identified putative Tdp1 inhibitors. Treatment of control human mammary epithelial cells and the breast cancer cell line MCF-7 with compound CD00509 preferentially sensitized MCF-7 cells to camptothecin and decreased cell proliferation 25% more than camptothecin treatment alone. This suggests that CD00509 specifically targeted Tdp1 in vitro, and CD00509 increased the sensitivity of wild-type murine embryonic fibroblasts (MEFs) to camptothecin to a degree comparable to that of Tdp1(-/-) MEFs. In addition, consistent with poly ADP-ribose polymerase-1 (PARP-1) collaborating with Tdp1 in DNA repair, combined Tdp1 and PARP-1 inhibition was more detrimental to MCF-7 cells than either treatment alone, whereas the combination was not additively harmful to control mammary cells. We conclude that targeting Tdp1 in anticancer therapy preferentially enhances the sensitivity of some breast cancer cells to camptothecin and may be an effective adjuvant for breast cancer therapy.
DNA修复通路的突变会促进肿瘤发生，并为肿瘤细胞中的合成致死相互作用提供治疗靶点。鉴于酪氨酰-DNA磷酸二酯酶1（Tdp1）可修复停滞的拓扑异构酶-I DNA复合物，我们推测抑制Tdp1在某些癌症中具有合成致死效应。为了验证这一点，我们在肿瘤阵列中筛选Tdp1的表达情况，发现Tdp1在许多肿瘤中都有表达，包括超过90%的人类乳腺肿瘤。随后的化学筛选确定了潜在的Tdp1抑制剂。用化合物CD00509处理对照人乳腺上皮细胞和乳腺癌细胞系MCF-7，MCF-7细胞对喜树碱的敏感性增强，细胞增殖比单独使用喜树碱处理减少了25%以上。这表明CD00509在体外特异性靶向Tdp1，并且CD00509使野生型小鼠胚胎成纤维细胞（MEFs）对喜树碱的敏感性增加到与Tdp1基因敲除的MEFs相当的程度。此外，与聚ADP-核糖聚合酶-1（PARP-1）在DNA修复中与Tdp1协作一致，联合抑制Tdp1和PARP-1对MCF-7细胞的损害比单独任何一种处理都更大，而这种联合对对照乳腺细胞并无累加性损害。我们得出结论，在抗癌治疗中靶向Tdp1可优先提高某些乳腺癌细胞对喜树碱的敏感性，可能是乳腺癌治疗的一种有效辅助手段。
